Download AssayMaxTM Mouse Leptin ELISA Kit

AssayMaxTM
Mouse Leptin ELISA Kit
Assaypro LLC
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St. Charles, MO 63301
T (636) 447-9175
F (636) 395-7419
www.assaypro.com
For any questions regarding troubleshooting or performing the assay, please contact our
support team at [email protected].
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Assay Summary
Step 1. Add 50 µl of Standard or Sample per well.
Incubate 2 hours.
Step 2. Wash, then add 50 µl of Biotinylated Antibody per well.
Incubate 2 hours.
Step 3. Wash, then add 50 µl of SP Conjugate per well.
Incubate 30 minutes.
Step 4. Wash, then add 50 µl of Chromogen Substrate per well.
Incubate 20 minutes.
Step 5. Add 50 µl of Stop Solution per well.
Read at 450 nm immediately.
Symbol Key
Consult instructions for use.
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Assay Template
Mouse Leptin ELISA Kit
Catalog No. EML2001-1
Sample insert for reference use only
Introduction
Leptin, a 16-kDa protein secreted from white adipocytes, has been implicated
in the regulation of food intake, energy expenditure, and whole-body energy
balance in rodents and humans (1). The plasma insulin response appears
more closely associated with the plasma leptin concentration (2). Neonatal
leptin levels are strongly associated with female gender, birth length, and
formula feeding (3). Leptin concentrations were higher in women than in men
(4).
Principle of the Assay
The AssayMax Mouse Leptin ELISA (Enzyme-Linked Immunosorbent Assay) kit
is designed for detection of mouse leptin in plasma, serum, and cell culture
samples. This assay employs a quantitative sandwich enzyme immunoassay
technique that measures mouse leptin in less than 5 hours. A polyclonal
antibody specific for mouse leptin has been pre-coated onto a 96-well
microplate with removable strips. Mouse leptin in standards and samples is
sandwiched by the immobilized antibody and a biotinylated polyclonal
antibody specific for mouse leptin, which is recognized by a streptavidinperoxidase conjugate. All unbound material is washed away and a peroxidase
enzyme substrate is added. The color development is stopped and the
intensity of the color is measured.
Caution and Warning
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This product is for Research Use Only and is Not For Use In Diagnostic
Procedures.
Prepare all reagents (working diluent buffer, wash buffer, standard,
biotinylated antibody, and SP conjugate) as instructed, prior to running
the assay.
Prepare all samples prior to running the assay. The dilution factors for
the samples are suggested in this insert. However, the user should
determine the optimal dilution factor.
Spin down the SP conjugate vial and the biotinylated antibody vial before
opening and using contents.
The Stop Solution is an acidic solution.
The kit should not be used beyond the expiration date.
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Reagents
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Mouse Leptin Microplate: A 96-well polystyrene microplate (12 strips of
8 wells) coated with a polyclonal antibody against mouse leptin.
Sealing Tapes: Each kit contains 3 precut, pressure sensitive sealing
tapes that can be cut to fit the format of the individual assay.
Mouse Leptin Standard: Mouse leptin in a buffered protein base (96 ng,
lyophilized).
Biotinylated Mouse Leptin Antibody (50x): A 50-fold concentrated
biotinylated polyclonal antibody against mouse leptin (110 l).
MIX Diluent Concentrate (10x): A 10-fold concentrated buffered protein
base (30 ml).
Wash Buffer Concentrate (20x): A 20-fold concentrated buffered
surfactant (30 ml, 2 bottles).
Streptavidin-Peroxidase Conjugate (SP Conjugate): A 100-fold
concentrate (80 l).
Chromogen Substrate: A ready-to-use stabilized peroxidase chromogen
substrate tetramethylbenzidine (8 ml).
Stop Solution: A 0.5 N hydrochloric acid to stop the chromogen
substrate reaction (12 ml).
Storage Condition
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Upon arrival, immediately store components of the kit at recommended
temperatures up to the expiration date.
Store SP Conjugate and Biotinylated Antibody at -20°C.
Store Microplate, Diluent Concentrate (10x), Wash Buffer, Stop Solution,
and Chromogen Substrate at 2-8°C.
Unused microplate wells may be returned to the foil pouch with the
desiccant packs and resealed. May be stored for up to 30 days in a
vacuum desiccator.
Diluent (1x) may be stored for up to 30 days at 2-8°C.
Store Standard at 2-8°C before reconstituting with Diluent and at -20°C
after reconstituting with Diluent.
Other Supplies Required
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Microplate reader capable of measuring absorbance at 450 nm.
Pipettes (1-20 l, 20-200 l, 200-1000 l, and multiple channel).
Deionized or distilled reagent grade water.
Sample Collection, Preparation, and Storage
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Plasma: Collect plasma using one-tenth volume of 0.1 M sodium citrate
as an anticoagulant. Centrifuge samples at 3000 x g for 10 minutes and
assay. Store the remaining samples at -20°C or below for up to 3 months.
Avoid repeated freeze-thaw cycles (EDTA or Heparin can also be used as
an anticoagulant).
Serum: Samples should be collected into a serum separator tube. After
clot formation, centrifuge samples at 3000 x g for 10 minutes. Remove
serum and assay. Store the remaining serum at -20°C or below for up to
3 months. Avoid repeated freeze-thaw cycles.
Cell Culture Supernatants: Centrifuge cell culture media at 3000 x g for
10 minutes to remove debris. Collect supernatants and assay. Store the
remaining samples at -20°C or below for up to 3 months. Avoid repeated
freeze-thaw cycles.
Reagent Preparation
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Freshly dilute all reagents and bring all reagents to room temperature
before use.
MIX Diluent Concentrate (10x): If crystals have formed in the
concentrate, mix gently until the crystals have completely dissolved.
Dilute MIX Diluent Concentrate 1:10 with reagent grade water. Store for
up to 30 days at 2-8°C.
Standard Curve: Reconstitute the 96 ng of Mouse Leptin Standard with 4
ml of MIX Diluent to generate a 24 ng/ml standard stock solution. Allow
the standard to sit for 10 minutes with gentle agitation prior to making
dilutions. Prepare duplicate or triplicate standard points by serially
diluting the standard stock solution (24 ng/ml) 1:2 with MIX Diluent to
produce 12, 6, 3, 1.5, 0.75, and 0.375 ng/ml solutions. MIX Diluent serves
as the zero standard (0 ng/ml). Any remaining solution should be frozen
at -20°C and used within 30 days.
Standard Point
P1
P2
P3
P4
P5
P6
P7
P8
Dilution
1 part Standard (24 ng/ml)
1 part P1 + 1 part MIX Diluent
1 part P2 + 1 part MIX Diluent
1 part P3 + 1 part MIX Diluent
1 part P4 + 1 part MIX Diluent
1 part P5 + 1 part MIX Diluent
1 part P6 + 1 part MIX Diluent
MIX Diluent
[Mouse Leptin] (ng/ml)
24.00
12.00
6.000
3.000
1.500
0.750
0.375
0.000
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Biotinylated Mouse Leptin Antibody (50x): Spin down the antibody
briefly and dilute the desired amount of the antibody 1:50 with MIX
Diluent. Any remaining solution should be frozen at -20°C.
Wash Buffer Concentrate (20x): If crystals have formed in the
concentrate, mix gently until the crystals have completely dissolved.
Dilute Wash Buffer Concentrate 1:20 with reagent grade water.
SP Conjugate (100x): Spin down the SP Conjugate briefly and dilute the
desired amount of the conjugate 1:100 with MIX Diluent. Any remaining
solution should be frozen at -20°C.
Assay Procedure
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Prepare all reagents, standard solutions, and samples as instructed. Bring
all reagents to room temperature before use. The assay is performed at
room temperature (20-25°C).
Remove excess microplate strips from the plate frame and return them
immediately to the foil pouch with desiccants inside. Reseal the pouch
securely to minimize exposure to water vapor and store in a vacuum
desiccator.
Add 50 l of Mouse Leptin Standard or sample per well. Cover wells and
incubate for 2 hours. Start the timer after the last addition.
Wash five times with 200 l of Wash Buffer manually. Invert the plate
each time and decant the contents; hit 4-5 times on absorbent material
to completely remove the liquid. If using a machine, wash six times with
300 l of Wash Buffer and then invert the plate, decanting the contents;
hit 4-5 times on absorbent material to completely remove the liquid.
Add 50 l of Biotinylated Mouse Leptin Antibody to each well and
incubate for 2 hours.
Wash the microplate as described above.
Add 50 l of Streptavidin-Peroxidase Conjugate per well and incubate for
30 minutes. Turn on the microplate reader and set up the program in
advance.
Wash the microplate as described above.
Add 50 l of Chromogen Substrate per well and incubate for 20 minutes
or till the optimal blue color density develops. Gently tap the plate to
ensure thorough mixing and break the bubbles in the well with pipette
tip.
Add 50 l of Stop Solution to each well. The color will change from blue
to yellow.
Read the absorbance on a microplate reader at a wavelength of 450 nm
immediately. If wavelength correction is available, subtract readings at
570 nm from those at 450 nm to correct optical imperfections.
Otherwise, read the plate at 450 nm only. Please note that some
unstable black particles may be generated at high concentration points
after stopping the reaction for about 10 minutes, which will reduce the
readings.
Data Analysis
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Calculate the mean value of the duplicate or triplicate readings for each
standard and sample.
To generate a standard curve, plot the graph using the standard
concentrations on the x-axis and the corresponding mean 450 nm
absorbance on the y-axis. The best-fit line can be determined by
regression analysis using log-log or four-parameter logistic curve-fit.
Determine the unknown sample concentration from the Standard Curve
and multiply the value by the dilution factor.
Standard Curve
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The curve is provided for illustration only. A standard curve should be
generated each time the assay is performed.
Mouse Leptin Standard Curve
OD 450 nm
10.0
1.0
0.1
0.1
1.0
10.0
100.0
[mLeptin] (ng/ml)
Performance Characteristics
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The minimum detectable level of mouse leptin is typically ~ 0.3 ng/ml.
Intra-assay and inter-assay coefficients of variation were 4.6% and 7.1%
respectively.
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Cross-Reactivity
Species
Canine
Bovine
Monkey
Mouse
Rat
Human
Rabbit
Cross Reactivity (%)
None
None
None
100%
<20%
<20%
None
References
(1)
(2)
(3)
(4)
Houseknecht KL et. al (1998) J Anim Sci. 76(5):1405-20.
Abbasi F et. al. (2000) Metabolism. 49(4):544-7
Petridou E et. al (2005) Clin Endocrinol (Oxf). 62(3):366-71
Wallerstedt SM et. al (2004) Blood Press 13(4):243-6
Version 2.7R1
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